Catheters and catheter systems are used for many types of medical procedures. In some catheter systems, the catheters are provided with retention members, to retain the catheters in place during use when inserted into the patient's/user's body. A common type of retention member for such catheters is an inflatable retention member, such as an inflatable balloon, arranged close to the insertable end of the catheter. A separate lumen is arranged within the catheter for transferring an inflation fluid from an external source, through the length of the catheter, and into the inflatable retention member for inflation, and for transferring the inflation fluid back though the length of the catheter during deflation of the inflatable retention member. The inflatable retention member is inflated to a suitable diameter with fluid, such as air, water or saline.
In addition to the lumen used for the inflation fluid, a second lumen may be provided to deliver e.g. irrigation fluid to the body cavity, for drainage of a liquid or the like, such as faeces in case of a rectal catheter or urine in case of a indwelling urinary catheter, from the body cavity, etc.
The inflatable retention member preferably surrounds the distal end of the catheter and preferably has a toroidal shape when fully inflated.
However, systems using an inflatable retention member must be used carefully because they can create too much pressure on the body rectal tissue if the retention balloon is over inflated. Accordingly, all such catheter systems must have an indicated maximum volume for the retention balloon that each manufacturer has established as safe. However, this maximum volume can be exceeded by over inflating the inflatable retention member, resulting in damage to the soft tissue surrounding the retention member. In particular, over inflation to such a level that the inflatable retention member explodes may be both harmful and painful, and may in severe cases even have lethal consequences. However, even without exploding, the inflated retention member can create discomfort, pain or even damage by creating too much pressure on the tissue in vicinity of the inflatable retention member.
Various attempts have been made over the years to propose solutions to better control the inflation of such inflatable retention members. However, most of these proposed solutions are very complex and costly to produce. Further, these known systems are still not able to provide the user with adequate possibilities to control the inflation, and at the same time ensuring that over inflation is avoided.
For example, US 2016/193403 by the same applicant discloses an irrigation system in which balloon inflation is controlled in accordance with pre-set inflation levels. However, the inflated size of the balloon may sometime vary from user to user, and also sometimes from time to time for the same user. Further, EP 2 683 424 discloses an electrically operated transanal irrigation system, where inflation of an inflatable balloon may be controlled by a pressure sensor. Still further, US 2014/0052063 discloses an irrigation system comprising a catheter with an inflatable balloon. A control system is provided for prevention of over-inflation of the balloon. To this end, the system monitors either the fluid pressure in the balloon as it is filled, or volume of fluid being provided to the balloon. Also, WO 2016/095929 discloses an electrically operated rectal irrigation system. It discloses the use of an electric pump for inflation of a balloon, and the pumping is controlled based on time duration or number of pump revolutions.
There is thus a need for improvements of the control of inflation of catheters having inflatable retention members in rectal irrigation systems, but also in other catheter systems having inflatable retention members, such as in urinary catheter systems, in endotracheal intubation systems, etc. In particular, there is a need for an irrigation device which can be used safely, easily and conveniently, and with improved controllability, for self-administration of the irrigation liquid, and which also preferably can be produced in a cost-efficient way.